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1.
用FDTD和物理光学混合法分析毫米波抛物面天线 总被引:6,自引:0,他引:6
抛物面天线通常的分析方法是几何光学法和物理光学法,对于电大尺寸的抛物面天线这两种方法都可以得到较好的结果,对于电小尺寸馈源的抛物面天线,馈源方向图不仅取决于辐射器本身的辐射特性,其馈电结构对馈源方向图也有较大的影响,在此情况下,用上述方法得到的结果与实验结果之间有较大的误差.利用FDTD可以把整个馈电结构纳入计算域中,得到辐射器完整的近区场,由等效原理可求出抛物面上电流分布,从而用物理光学方法计算抛物面天线远区场.本文用这种混合方法分析计算了毫米波波导裂缝作为辐射器的抛物面天线,计算结果和测试结果相当吻合,证明了方法的有效性. 相似文献
2.
桁架式可展开反射面天线在未来的星载合成孔径雷达(SAR)中将有着广泛应用,然而目前对该类天线方向图的系统性理论分析还不够完善.该文根据桁架式天线反射面的特殊构型——空间三角形单元拓扑结构,提出了一种将物理光学法与换元法相结合来计算馈源数目任意、位置任意的桁架式天线方向图的方法,仅需反射面上的节点坐标即可求出天线方向图.对矩形喇叭线阵馈源激励下的口径大小为2.8 m×6 m 的桁架式可展开反射面天线方向图进行编程仿真,得到的主要参数计算值与实测值相吻合,通过与几何光学法仿真结果相比较,得出该文提出的算法更为精确有效.该文提出的算法建立了桁架式天线反射面结构与天线方向图的直接联系,实现了该类天线的机电一体化设计. 相似文献
3.
Boriskin A.V. Godi G. Sauleau R. Nosich A.I. 《Antennas and Propagation, IEEE Transactions on》2008,56(2):485-492
We assess the accuracy and relevance of the numerical algorithms based on the principles of geometrical optics (GO) and physical optics (PO) in the analysis of reduced-size homogeneous dielectric lenses prone to behave as open resonators. As a benchmark solution, we use the Muller boundary integral equations (MBIEs) discretized with trigonometric Galerkin scheme that has guaranteed and fast convergence as well as controllable accuracy. The lens cross-section is chosen typical for practical applications, namely an extended hemiellipse whose eccentricity satisfies the GO focusing condition. The analysis concerns homogeneous lenses made of rexolite, fused quartz, and silicon with the size varying between 3 and 20 wavelengths in free space. We consider the 2D case with both - and -polarized plane waves under normal and oblique incidence, and compare characteristics of the near fields. 相似文献
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几何光学是信息工程(光电)专业的学生所面临的第一门专业基础课程。本文以培养学生的工程素质为出发点,探讨了几何光学教学的有关问题。作者在该课程的教学中结合工程实际的需要,向学生提出实际课题,引导学生主动地学习,在现有资源的基础上寻找解决问题的正确方向,以团队合作的方式积极参与科研开发,描述自己的方案并与其他小组讨论。实践证明,这种教学方式在培养学生学习与发展的能力、分析问题与创造性地解决工程问题的能力等方面具有积极作用。 相似文献
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几何光学是信息工程(光电)专业的学生所面临的第一门专业基础课程。本文以培养学生的工程素质为出发点,探讨了几何光学教学的有关问题。作者在该课程的教学中结合工程实际的需要,向学生提出实际课题, 引导学生主动地学习,在现有资源的基础上寻找解决问题的正确方向,以团队合作的方式积极参与科研开发,描述自己的方案并与其他小组讨论。实践证明,这种教学方式在培养学生学习与发展的能力、分析问题与创造性地解决工程问题的能力等方面具有积极作用。 相似文献
6.
“物理光学”教学设计的研究 总被引:2,自引:0,他引:2
“物理光学”课程讲述了波动光学的基本理论,是电子科学与技术专业后续课程的重要基础。通过对本课程的学习,使学生进一步认识光的物理本质和基本规律,掌握基本的分析方法,培养学生分析与解决相关专业问题的能力,为相关的专业课程学习或深入研究打下必要的基础。根据物理光学课程特点,我们对本门课程的教学设计进行了有益探讨,并在教学中取得良好的教学效果。 相似文献
7.
Shape Reconstruction of Three-Dimensional Conducting Curved Plates Using Physical Optics, NURBS Modeling, and Genetic Algorithm 总被引:1,自引:0,他引:1
《Antennas and Propagation, IEEE Transactions on》2006,54(9):2497-2507
A microwave inverse scattering problem including a method for shape reconstruction of three-dimensional electrically large conducting patches with simple geometries using genetic algorithm is presented. Unknown shape reconstruction algorithm starts from the knowledge of the simulated radar cross-section (RCS) data through back-scattering far-field computation using physical optics approximation. The forward problem involves the computation of the multiple-frequency and multiple-direction RCS of three-dimensional large conducting patches modeled by nonuniform rational B-spline (NURBS) surfaces. The control points of NURBS are the geometrical parameters, which are optimized for the shape reconstruction procedure. The extended stationary phase method and critical cases, which occur in physical optics computations in the forward problem, are also discussed. Noise effect and the influence of increment in the number of control points of a NURBS over the inversion algorithm are investigated as well. Numerical results are presented to verify the operation of the proposed algorithm. 相似文献
8.
机载超宽带天线罩物理光学分析方法 总被引:6,自引:0,他引:6
该文提出了机载超宽带天线罩口径积分-表面积分-自适应网格(AI-SI-AG)分析方法。给出了用AI-SI-AG的计算和实测结果。理论分析和实验结果表明,该算法能够高效地预测定向和全向天线的带罩方向图,理论计算与实际测试符合较好,在工程应用中有较大的实用价值。 相似文献
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《Antennas and Propagation Magazine, IEEE》2008,50(3):11-20
The physical optics approximation is widely used in analysis of antennas and scattering problems for electromagnetic and acoustic waves. The present paper investigates the nature of this classical approximation. It is shown that the scattered field in this approximation can be separated into two parts: the reflected field, containing all reflected rays and beams, and the shadow radiation, responsible for the Fresnel diffraction and the forward scattering. This observation elucidates the physics behind the fundamental diffraction law related to the total power scattered by large reflecting objects. It also clarifies the diffraction limit for reduction of scattering by absorbing materials. 相似文献
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"工程光学"教学改革初探与实践 总被引:2,自引:0,他引:2
"工程光学"课程讲述了几何光学和波动光学的基本理论,是电子科学与技术专业的必修基础课。"工程光学"具有抽象性强和枯燥乏味等特点,给教学带来了一定的难度;且"工程光学"也是一门专业性很强的课,侧重于对实际光学问题的解释。根据该课程特色,针对电子科学与技术专业学生的特点,探讨了教学内容、教学条件、教学方法和教学手段等方面的教学改革,并总结了取得的成绩和存在的问题。 相似文献
13.
Time-Reversal Detection Using Antenna Arrays 总被引:1,自引:0,他引:1
《Signal Processing, IEEE Transactions on》2009,57(4):1396-1414
14.
Shankar P. Mohana Gupta Suresh N. Gupta H. M. 《IEEE transactions on bio-medical engineering》1982,(1):8-15
Coherent optics and holography have become potential tools in offering tangible solutions to various problems in science, engineering, and medicine. Holography, with its three-dimensional nature and high resolution, finds applications in microscopy and macroscopy. Various holographic interferometric techniques are highly useful in diagnostic medicine. Coherent optical processors have remarkably high speeds and offer a parallel processing facility. Accordingly, these processors should be of great use in biomedical data processing like spectral analysis, correlation, image enhancement, etc. A survey of these techniques and their typical applications to problems in biomedical engineering has been given. 相似文献
15.
生物样品折射率的空间变化导致了光学畸变的产生,这种畸变对于共聚焦显微镜观察厚的生物样品和活体体内组织成像是一种严重的限制。自适应光学(AO)技术是通过快速反应的变形镜使镜面发生形变来补偿像差,在共聚焦显微镜中应用自适应光学技术可以校正光学畸变,观察深层组织活动,进行活体成像和实时检测。详细分析了共聚焦显微镜中像差的来源及光学畸变的特点,讨论了目前在共聚焦显微镜中自适应光学校正的方案及研究现状,讨论了共聚焦显微镜中自适应光学的波前传感器、畸变测量和波前校正器,并探讨了目前超高分辨率显微成像技术的发展方向。 相似文献
16.
Lin James C. Yu Francis T. S. Tai Anthony M. 《IEEE transactions on bio-medical engineering》1978,(3):243-249
It has been shown that ultrasonic Doppler signals can be obtained easily and transcutaneously from many blood vessels in both normal and atherosclerotic subjects. The Doppler spectrum changes with time, giving rise toa distnbution of frequencies whose envelope has a waveform that is characteristic of the vessel site and closely folows the events of the cardiac cycle. This makes it very useful in diagnosing lesions of the arterial system. The paper presents a coherent optical technique for displaying and analyzing a blood-flow-generated ultrasonic Doppler spectrum. The system is highly cost-effective and produces spectrograms on-line. Other advantages include a large, continuously variable bandwidth, an instantaneous display of velocity profile, and simultaneous display of temporal spectra. The system makes use of the Fourier transformation property of converging lens and its use of processing time signals. The spectrum obtained from the brachial artery of a normal subject compares favorably with the spectrograms obtained using electronic spectrum analyzers. 相似文献
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针对近空间飞行器测控的需求,设计了一种Ka频段的宽角覆盖多波束天线。采用方喇叭作为馈源,通过馈源的横向偏焦,实现反射面天线的宽角覆盖;最后,仿真并研制了原理样机,进行了测试。测试结果表明,该多波束天线覆盖了±1.5°以上的空域,且在覆盖区内的增益差小于1.8 dB,实现了对探测空域的宽角高增益覆盖。样机的研制成功为后续的工程优化提供了重要的设计参考。 相似文献
18.
涂层目标散射的双站物理光学公式及其散射矩阵 总被引:2,自引:1,他引:1
本文从物理光学基本假设与阻抗边界条件出发,建立了涂覆雷达吸波材料(RAM)的任意三维光滑凸型导电物体散射的基本双站公式。公式是从Fresnel反射系统及阻抗边界条件推导的。本文同时得到了涂层物体表面入射场及其同几何结构导体表面入射场之间的关系与电、磁流比系数关系。文末给出了用基本双站公式计算电大物体双站散射矩阵与双站散射截面的计算方法与计算实例。 相似文献
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